linux-kernel - Re: [PATCH] platform/x86: hp-bioscfg: Fix error handling in hp_add_other

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Date:   Fri, 10 Nov 2023 19:24:01 +0530
From:   Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
To:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc:     Jorge Lopez <jorge.lopez2@...com>,
        Hans de Goede <hdegoede@...hat.com>,
        Mark Gross <markgross@...nel.org>,
        Thomas Weißschuh <linux@...ssschuh.net>,
        platform-driver-x86@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>, dan.carpenter@...aro.org,
        kernel-janitors@...r.kernel.org, error27@...il.com,
        kernel test robot <lkp@...el.com>
Subject: Re: [PATCH] platform/x86: hp-bioscfg: Fix error handling in
 hp_add_other_attributes()

Hi Ilpo,

On 10/11/23 6:45 pm, Ilpo Järvinen wrote:
> On Fri, 10 Nov 2023, Harshit Mogalapalli wrote:
> 
>> 1. acpi_object *obj is unused in this function, so delete it, also
>>     delete a unnecessary kfree(obj);
>> 2. Fix a memory leak of 'attr_name_kobj' in the error handling path.
>> 3. When kobject_init_and_add() fails on every subsequent error path call
>>     kobject_put() to cleanup.
>>
>> Fixes: a34fc329b189 ("platform/x86: hp-bioscfg: bioscfg")
>> Reported-by: kernel test robot <lkp@...el.com>
>> Reported-by: Dan Carpenter <error27@...il.com>
>> Closes: https://lore.kernel.org/r/202309201412.on0VXJGo-lkp@intel.com/
>> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@...cle.com>
>> ---
>> This is only compile tested, based on static analysis.
>> ---
>>   drivers/platform/x86/hp/hp-bioscfg/bioscfg.c | 14 ++++++--------
>>   1 file changed, 6 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
>> index 5798b49ddaba..b28e52b64690 100644
>> --- a/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
>> +++ b/drivers/platform/x86/hp/hp-bioscfg/bioscfg.c
>> @@ -588,7 +588,6 @@ static void release_attributes_data(void)
>>   static int hp_add_other_attributes(int attr_type)
>>   {
>>   	struct kobject *attr_name_kobj;
>> -	union acpi_object *obj = NULL;
>>   	int ret;
>>   	char *attr_name;
>>   
>> @@ -596,8 +595,8 @@ static int hp_add_other_attributes(int attr_type)
>>   
>>   	attr_name_kobj = kzalloc(sizeof(*attr_name_kobj), GFP_KERNEL);
>>   	if (!attr_name_kobj) {
>> -		ret = -ENOMEM;
>> -		goto err_other_attr_init;
>> +		mutex_unlock(&bioscfg_drv.mutex);
> 
> I don't understand why this has to be inside the mutex at all, cannot
> you just move it outside of the mutex and then there's no need to unlock?
> 

Oh right, I think this allocation can be done without a lock.

Will move this down in my v2.

Thanks for the suggestion.

Regards,
Harshit

>> +		return -ENOMEM;
>>   	}
>>   
>>   	/* Check if attribute type is supported */
>> @@ -614,15 +613,15 @@ static int hp_add_other_attributes(int attr_type)
>>   
>>   	default:
>>   		pr_err("Error: Unknown attr_type: %d\n", attr_type);
>> -		ret = -EINVAL;
>> -		goto err_other_attr_init;
>> +		kfree(attr_name_kobj);
>> +		mutex_unlock(&bioscfg_drv.mutex);
>> +		return -EINVAL;
> 
> Add a new label for unlock and goto to it instead.
> 
>>   	}
>>   
>>   	ret = kobject_init_and_add(attr_name_kobj, &attr_name_ktype,
>>   				   NULL, "%s", attr_name);
>>   	if (ret) {
>>   		pr_err("Error encountered [%d]\n", ret);
>> -		kobject_put(attr_name_kobj);
>>   		goto err_other_attr_init;
>>   	}
>>   
>> @@ -647,10 +646,9 @@ static int hp_add_other_attributes(int attr_type)
>>   
>>   	mutex_unlock(&bioscfg_drv.mutex);
>>   	return 0;
>> -
>>   err_other_attr_init:
>> +	kobject_put(attr_name_kobj);
> 
> unlock:
> 
>>   	mutex_unlock(&bioscfg_drv.mutex);
>> -	kfree(obj);
>>   	return ret;
>>   }
>>   
>>
> 
>